Many appliances include pumps for flowing fluid therethrough during operation of the appliance. One example is a washing machine appliance, which includes a pump for draining fluid from a tub of the washing machine appliance. Washing machine appliances generally include a cabinet which supports a tub for containing wash fluid, e.g., water and detergent, bleach and/or other wash additives. A basket is mounted within the tub and defines a wash chamber for receipt of a load of articles for washing. During operation of such washing machine appliances, wash fluid is directed into the tub and onto articles within the wash chamber of the basket. The basket or an agitation element can rotate at various speeds to agitate articles within the wash chamber in the wash fluid, to wring wash fluid from articles within the wash chamber, etc. The fluid can then be drained from the tub, and a pump is typically provided for facilitating such drainage. Another example of an appliance which utilizes a pump is a dishwasher appliance which can utilize a pump for drainage and/or recirculation purposes.
One issue with many presently known pumps is that the pumps generally run continuously during a drain cycle of the appliance. In some cases, insufficient fluid levels may flow through the pump during a portion of the drain cycle. For example, there may be blockage in the system which prevents or reduces fluid flow through the pump, or the amount of fluid to be drained may be low, resulting in a majority of the fluid being flowed through the pump in a faster than expected time period. These situations may result in the pump running “dry” for period of time, which can cause damage to the pump and can utilize excess energy. In some cases, pressure sensors are provided for detecting blockages in the system, but these sensors typically only provide a blockage indication to the user when a full blockage is detected in the appliance.
Accordingly, improved appliance pump operation is desired. In particular, pump assemblies, methods and appliances which facilitate sensing of low fluid flow levels within pumps would be advantageous.